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Ionospheric Focusing for an Antenna in the Presence of the Geomagnetic Field
Author(s) -
Walsh D.,
Weil Herschel
Publication year - 1968
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1002/rds196839936
Subject(s) - ionosphere , earth's magnetic field , antenna (radio) , antenna gain , physics , ionospheric heater , dipole antenna , refraction , numerical integration , optics , geophysics , geology , computational physics , magnetic field , mathematics , antenna aperture , mathematical analysis , computer science , telecommunications , quantum mechanics
A geometrical optics treatment of ionospheric focusing is presented which is exact within the assumptions of horizontal stratification of the ionosphere and of the collision‐free Appleton‐Hartree equation. In addition to effects of ray refraction, the expression derived for gain distribution in the beam outside the ionosphere includes in a natural manner the directional characteristics of the antenna in the plasma. These involve both the antenna geometry and the characteristic polarizations of the incident waves. The factors in the gain expression which are dependent only on the plasma characteristics are expressed in closed form. Evaluation of the remaining factors, in general, requires knowledge of the current distribution on the antenna. For the case of an electrically short dipole, this evaluation is carried out and the gain distribution expressed in closed form, apart from a normalizing factor that can only be determined by numerical integration. The properties of the gain distribution are illustrated by contour plots.